LINQ Distinct(), but programmatically select a winner

Question

I found this posting, regarding selecting a distinct item based on a particular property.

The following will look in my "results" list, group them by ID, and select the first one as the winner.

results.GroupBy(r => r.ID).Select(g => g.First()).ToList();

But, how can I conditionally select the winner?

For example, each result contains a property called Language.Name.

When selecting distinct results, I want to pick the one where result.Language.Name.ToLower() == regionalISOCode as the winner if it exists.

If it does not exist, then the result.Language.Name.ToLower() == "en" should be selected as the winner.

what`s the question again ? – Modar Na Mar 21 '17 at 18:11 — Modar Na, Mar 21 '17 at 18:11
`g.First()` is programmatically selecting the winner. – Cory Nelson Mar 21 '17 at 18:22 — Cory Nelson, Mar 21 '17 at 18:22

score 6 · Accepted Answer · answered Mar 21 '17 at 18:13

6

You just need to change the Select():

results
    .GroupBy(r => r.ID)
    .Select(g => g.FirstOrDefault(r => r.Language.Name.ToLower() == regionalISOCode) ??
                 g.First(r => r.Language.Name.ToLower() == "en"))
    .ToList();

answered Mar 21 '17 at 18:13

itsme86

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LINQ Distinct(), but programmatically select a winner

1 Answers1